The debate over pre-filling butt joints before taping, used to think it was a waste of time

For years I was skeptical about pre-filling those butt joints before throwing tape on them. I figured the mud under the tape would do the same job and it just saved me an extra step. Then I did a big basement job in Columbus last winter and the homeowner was super picky about flatness. I tried pre-filling half the joints and doing the other half my old way just to see the difference. After sanding I could tell the pre-filled ones needed way less mud on top and the bubbles were almost nonexistent. Now I do it on every butt joint and it cuts down on at least one coat for me. Anyone else go back and forth on this or am I just late to the party?

2 comments

2 Comments

tessap981mo ago

Oh man, you are definitely not late to the party, I went through the exact same thing. I used to skip pre-filling too because I thought it was just extra work and the tape would flatten everything out anyway. But after doing a big drywall job at my buddy's house where the walls were super uneven, I tried pre-filling the butts on one wall and leaving the other wall alone. The difference was crazy - the pre-filled ones barely needed any sanding and the tape laid down so smooth without those air pockets. Now I won't even start a butt joint without packing some mud in there first, it saves me so much time on the back end. I swear it's like the one trick that actually makes your life easier instead of harder once you get the hang of it.

christopher3851mo ago

I see it different. Pre-filling adds an extra step that I just don't need. The tape and mud do the job fine if you work it right and make sure the tape beds in full. I've been doing this for like 15 years and tried pre-filling plenty of times but I always ended up with more work because the pre-fill would shrink and leave a dip anyway. Then you're either throwing another coat on that dip or sanding it flat which adds time. I'd rather just use a wider knife and a tighter mud mix when I tape, get the air out with good pressure, and move on. Never had issues with bubbles or cracking that way. To each their own but I think pre-filling is solving a problem that good technique already handles.